During melanoma metastasis, tumor cells originating in the skin migrate via lymphatic vessels to the sentinel lymph node (sLN). This process facilitates tumor cell spread across the body. Here, we characterized the innate inflammatory response to melanoma in the metastatic microenvironment of the sLN. We found that macrophages located in the subcapsular sinus (SS) produced protumoral IL1α after recognition of tumoral antigens. Moreover, we confirmed that the elimination of LN macrophages or the administration of an IL1α-specific blocking antibody reduced metastatic spread. To understand the mechanism of action of IL1α in the context of the sLN microenvironment, we applied single-cell RNA sequencing to microdissected metastases obtained from animals treated with the IL1α-specific blocking antibody. Among the different pathways affected, we identified STAT3 as one of the main targets of IL1α signaling in metastatic tumor cells. Moreover, we found that the antitumoral effect of the anti-IL1α was not mediated by lymphocytes because Il1r1 knockout mice did not show significant differences in metastasis growth. Finally, we found a synergistic antimetastatic effect of the combination of IL1α blockade and STAT3 inhibition with stattic, highlighting a new immunotherapy approach to preventing melanoma metastasis.
HIKESHI-related hypomyelinating leukodystrophy (HHL) is a life-threatening disorder caused by homozygous pathogenic variants in HIKESHI. Symptoms include infantile onset progressive spastic dystonic quadriplegia, nystagmus, failure to thrive, diffused hypomyelination, and severe morbidity or death following febrile illness. V54L variants in HIKESHI are particularly prevalent within the Ashkenazi Jewish population. Here, we identified a novel P78S disease-causing variant in HIKESHI in a patient of Christian Arab origin, presenting with clinical and radiologic features characteristic of HHL. In silico analysis suggests that the mutated residue may affect the HIKESHI protein’s dimerization domain. We generated a comprehensive set of induced pluripotent stem cells (iPSCs) from the index case and two additional HHL patients. To investigate mechanisms potentially linked to febrile illness in HHL, we used these cells to study the heat shock (HS) response. HHL-iPSCs showed dramatically decreased levels of HIKESHI compared with healthy controls following HS. In addition, they exhibited increased HSP70 mRNA levels in response to HS, suggesting an increased sensitivity. HHL-iPSCs had impaired HSP70 translocation to the nucleus. Our results provide a human-relevant model for HHL.